Sodium ethylenesulphonate

Endpoint summary

Description of key information

Based on the available physico-chemical and toxicological data, sodium ethylenesulphonate (SVS) is considered to be bioavailable after oral absorption. Absorption after inhalation of SVS in its vapour state is not much likely due to its low vapour pressure. Dermal absorption of SVS in toxicologically relevant amounts is unlikely. Following uptake the compound can be distributed through the body thereby a pronounced metabolism is not expected. Excretion of VSN occurs most likely rapidly via urine.

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Absorption rate - oral (%):

100

Absorption rate - dermal (%):

50

Absorption rate - inhalation (%):

100

Additional information

In line with chapter R.7 c (ECHA, 2012) the main toxicokinetic properties of sodium ethylenesulphonate (SVS, CAS-No. 3039-83-6) are assessed on the basis of its physico-chemical properties and with special regard to the results of the standard toxicity studies performed with this substance. Specific toxicokinetics or dermal absorption studies are not available for the substance.

1. Relevant physico-chemical properties of SVS

Molecular weight: 130.1 g/mol

Physical state: liquid (RT)

logPow: -1.01

Water solubility: > 1000 g/L (20 °C)

Vapour pressure: 0.000391 Pa (20 °C)

2. Absorption

Oral

Based on its low molecular weight of 130 g/mol SVS is likely to be absorbed in the GI tract since small molecular weights below 500 g/mol do favour absorption. This assumption is supported by the results of the key acute oral toxicity study (Hoechst AG (a), 1976) indicating signs of systemic toxicity like semi prone position and lustreless coat in dose levels of 3750 mg/kg bw (dose level in terms of pure SVS). Due to the very high water solubility (1000 g/L) SVS will readily dissolve into the gastrointestinal fluids. However, absorption by passive diffusion may be limited by the rate at which the substance partitions out of the gastrointestinal fluid. This is in line with the borderline log Pow value of – 1.01 since absorption by passive diffusion generally requires a moderate log Pow value between -1 and 4.

Inhalation

Due to the very low vapour pressure of SVS and the resulting low volatility, an inhalation exposure of the compounds vapour phase is rather unlikely. In addition, if small amounts of the substance would reach the lungs in its vapour state and/or liquide aerosol the substance would be quantitatively absorbed based on the relevant physico-chemical characteristics outlined above for the oral route (retained within the mucous due to the very high water solubility).

Dermal

With respect to the very high water solubility and the log Pow of -1.01 the dermal uptake of SVS will be low since substances with a water solubility above 10 g/L and a log Pow value below 0 may be too hydrophilic to cross the lipid rich environment of the stratum corneum. A limited dermal absorption is supported by the result of an acute dermal toxicity study (Huntingdon Research Centre Ltd. (b), 1993) performed on rats. During the study no mortality and no systemic toxic effects were observed during the study period (24h treatment, 14-day observation) for the highest dose of 500 mg/kg bw (dose level in terms of pure SVS).

3. Distribution/Metabolism

In view of the clinical signs observed in the acute toxicity study (Hoechst AG (a), 1976) distribution of SVS in the body cannot be ruled out. However, since SVS revealed a moderate molecular size and a very hydrophilic character a wide distribution and diffusion across the membranes, particularly in fatty tissues, are not expected. Generally, metabolism will render a xenobiotic molecule more polar and harmless, leading to fast and quantitative excretion. For SVS, no conversion into a metabolite that was more cytotoxic or more genotoxic than the parent substance was noted when comparing in vitro test results with metabolic activation to in vitro test results without metabolic activation system (genetic toxicity tests). Thus, the formation of reactive metabolites is unlikely.

4. Excretion

The log Pow of -1.01, the high water solubility and the molecular weight below 300 g/mol indicate that SVS has no bioaccumulation potential and that rapid urinary excretion will be the most relevant route of excretion.

5. Generic absorption rates

Based on the above information and due to the fact that there are no specific toxicokinetic data available it is assumed that oral and inhalation absorption are comparable. Conservatively, it is assumed that dermal absorption is 2-fold lower than oral or inhalation absorption, even though the data suggest a much higher difference between dermal and oral/inhalation absorption.